Semiconductor device

ABSTRACT

A semiconductor device is disclosed that includes a substrate; a first semiconductor region arranged in the cell region on a first surface side of the substrate; a second semiconductor region arranged in a cell region; a channel stopper electrode arranged in a termination region; a first electrode arranged on the first surface and electrically connected to the second semiconductor region; an insulation film arranged between the channel stopper electrode and the first electrode; first conductors arranged inside the insulation film; second conductors arranged on the insulation film; and a second electrode arranged on a second surface side of the substrate. A width of an overlapping portion in a height direction of the first conductor and the second conductor on the first electrode side is larger than a width of an overlapping portion in the height direction of the first and second conductors on the channel stopper electrode side.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority based on 35 USC 119 from prior JapanesePatent Application No. 2018-219023 filed on Nov. 22, 2018, entitled“SEMICONDUCTOR DEVICE”, the entire contents of which are incorporatedherein by reference.

BACKGROUND

The disclosure relates to a semiconductor device, or more specifically,to a semiconductor device designed to improve reliability.

FIG. 1 of Japanese Patent Application Publication No. 2007-59766 (PatentDocument 1) discloses an insulated gate bipolar transistor (IGBT) whichincludes trenches 7 formed in a peripheral portion 6 and achieves highwithstand voltage. Here, second trench conductors 27 are coupled to oneanother by using capacitive coupling conductor layers 29, and electricpotentials of the second trench conductors 27 vary by changing positionsand sizes of the capacitive coupling conductor layers 29. Since thecapacitive coupling conductor layers 29 that are adjustable in size andin position are provided, it is possible to obtain an ideal depletionlayer and ideal electric field distribution to improve the withstandvoltage, which allegedly facilitate design and manufacturing of the IGBT(paragraph 0043 in Patent Document 1).

SUMMARY

A semiconductor device according to one or more embodiments including acell region and a termination region arranged around the cell regioncomprises: a substrate; a first semiconductor region of a firstconductivity type arranged in the cell region on a first surface side ofthe substrate; a second semiconductor region of a second conductivitytype arranged in the cell region on the first surface side of thesubstrate; a channel stopper electrode arranged in the terminationregion on the first surface side of the substrate; a first electrodearranged on the first surface of the substrate and electricallyconnected to the second semiconductor region; an insulation filmarranged between the channel stopper electrode and the first electrodein the termination region of the substrate; first conductors arrangedinside the insulation film; second conductors arranged on the insulationfilm; and a second electrode arranged on a second surface side of thesubstrate, in which a width of an overlapping portion in a heightdirection of one of the first conductors and one of the second conductoron the first electrode side is larger than a width of an overlappingportion in the height direction of one of the first conductors and thesecond conductor on the channel stopper electrode side.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating a plan view of a semiconductor deviceaccording to one or more embodiments;

FIG. 2 is a diagram illustrating a cross-sectional view of asemiconductor device 1 according to one or more embodiments;

FIG. 3 is a diagram illustrating a cross-sectional view of an enlargedpart of FIG. 2;

FIG. 4 is a diagram illustrating a cross-sectional view of asemiconductor device 2 according to one or more embodiments;

FIG. 5 is a diagram illustrating electric potential distribution in atermination region; and

FIG. 6 is another diagram illustrating the electric potentialdistribution in the termination region.

DETAILED DESCRIPTION

One or more embodiments are explained below in detail with reference todrawings. In the following description of the drawings, identical orsimilar elements may be denoted by identical or similar referencenumbers. It is to be noted, however, that the drawings are merelyschematic and thickness and dimensional relations, thickness ratiosamong layers, and the like are just examples and are not intended tolimit the technical ideas of this disclosure. In addition, dimensionalrelations and ratios may also vary among the drawings. While thefollowing embodiment describes an example in which a first conductivitytype represents an n-type while a second conductivity type represents ap-type, there is also a case in which the first conductivity type may bethe p-type while the second conductivity type may be the n-type byselecting an inverted conductivity-type relation. In the followingdescription, expressions an “upper side”, a “lower side”, a “rightside”, a “left side”, and the like may be used as appropriate based onthe drawings to be referred to. However, these expressions are notintended to limit the technical ideas of the disclosure. Meanwhile, thex axis and the y axis indicated in the drawings may be used to describedirections. Here, regarding cross-sectional views in particular, a“lateral direction” or a “longitudinal direction” may representdirections opposite to the x direction or the y direction indicated inthe drawings. In the meantime, a “depth direction” may represent the ydirection indicated in the drawings while a “height direction” mayrepresent the opposite direction to the y direction.

FIG. 1 is a diagram illustrating a plan view of a semiconductor deviceaccording to one or more embodiments. This semiconductor device includesa cell region (an active region) 300 arranged at the center, an emitterelectrode 127 arranged on the cell region 300 while extending outwardtherefrom, a first interlayer insulation film 123 arranged on an outerperipheral portion of the emitter electrode 127, and a channel stopperelectrode 129 arranged on an outer peripheral portion of the firstinterlayer insulation film 123. Here, the cell region 300 may include aprincipal part of an insulated gate bipolar transistor (IGBT), forexample. However, without limitation to the foregoing, the cell region300 may also be realized in the form of any of a diode, a Schottkybarrier diode (SBD), a metal-oxide-semiconductor field-effect transistor(MOSFET), and the like. The first interlayer insulation film 123 and thechannel stopper electrode 129 are arranged in such a way as to surroundthe cell region 300. A structure including a portion of the emitterelectrode 127, the first interlayer insulation film 123, and the channelstopper electrode 129 arranged on and extending outward from the cellregion 300 may also be referred to as a termination region asappropriate. In the embodiment of FIG. 1, the cell region 300 has arectangular shape. However, without limitation to the foregoing, thecell region 300 may also be realized in any of a square shape, acircular shape, an oval shape, and the like. Meanwhile, each of fourcorners of the rectangle of the termination region is formed into aright angle in the embodiment of FIG. 1. However, without limitation tothe foregoing, each corner may be formed into a rounded shape such as aquarter circle. Note that FIG. 1 does not indicate a protection film(not illustrated) for the convenience of explanation. However, such aprotection film may be arranged in such a way as to cover at least partof the cell region 300 as well as the termination region.

FIG. 2 is a diagram illustrating a cross-sectional view of asemiconductor device 1 according to one or more embodiments, which istaken along the H-H line in FIG. 1. This cross-sectional viewillustrates cross-sectional portions of the cell region 300 and atermination region 400 of the IGBT. In comparison with FIG. 1, theembodiment of FIG. 2 represents a structure in which part of the emitterelectrode 127, the first interlayer insulation film 123, and the channelstopper electrode 129 are covered with a protection film 151. Thesemiconductor device 1 illustrated in FIG. 2 includes: a collectorelectrode 101 arranged on a second surface side of a substrate 100; acollector layer 103 of the second conductivity type arranged on thecollector electrode 101 in the substrate 100; a field stop layer 105 ofthe first conductivity type arranged on the collector layer 103; a driftlayer 107 of the first conductivity type arranged on the field stoplayer 105 and having a lower impurity concentration than that of thefield stop layer 105; a base region 109 of the second conductivity typeprovided on the drift layer 107 and on the cell region 300 side; areduced surface layer 111 of the second conductivity type arranged onthe drift layer 107 and on an end portion side (the termination region400) of the substrate 100 in such a way as to come into contact with thebase region 109, and having a lower impurity concentration than that ofthe base region 109; and a channel stopper region 113 of the firstconductivity type provided on the drift layer 107 and on the end portionside (the termination region 400) of the substrate 100. Here, acombination of the collector layer 103, the field stop layer 105, thedrift layer 107, the base region 109, the reduced surface layer 111, andthe channel stopper region 113 mentioned above may be simply andconceptually referred to as the substrate 100. The cell region 300includes grooves that penetrate the base region 109 and reach the driftlayer 107, gate electrodes 112 arranged inside the grooves by theintermediary of insulation films 108, and emitter regions 110 of thefirst conductivity type provided on the base region 109 adjacent to thegrooves. Meanwhile, the termination region 400 of the semiconductordevice 1 between the emitter electrode 127 and the channel stopperelectrode 129 includes: a first insulation film 115 arranged on the baseregion 109, the reduced surface layer 111, the channel stopper region113, and on a portion of the drift layer 107 between the reduced surfacelayer 111 and the channel stopper region 113; a first conductor group121 including first conductors 121 a, 121 b, 121 c, 121 d, and 121 earranged on the first insulation film 115 and separated from oneanother; a second insulation film 119 arranged in such a way as to coverthe first conductor group 121; a second conductor group 125 includingsecond conductors 125 a, 125 b, 125 c, 125 d, and 125 e arranged on thesecond insulation film 119 and separated from one another; a line 131electrically connected to the second conductor 125 e on the channelstopper electrode 129 side; the first interlayer insulation film 123arranged in such a way as to cover part of the second conductor 125 a aswell as the second conductors 125 b, 125 c, 125 d, and the like; theemitter electrode 127 provided on the base region 109 in such a way asto come into contact with the second conductor 125 a on the emitterelectrode 127 side; a line 117 electrically connected to the line 131;the channel stopper electrode 129 provided in such a way as to come intocontact with the line 117 and the channel stopper region 113; and theprotection film 151 provided in such a way as to cover the firstinterlayer insulation film 123 and the channel stopper electrode 129 aswell as at least part of the emitter electrode 127.

The collector electrode 101 is electrically connected to the collectorlayer 103. The emitter electrode 127 is electrically connected to eitherthe emitter regions 110 or both the emitter regions 110 and the baseregion 109. The first interlayer insulation film 123 may adopt non-dopedsilicate glass (NSG), boron phosphor silicate glass (BPSG), or acombination thereof.

Dimensions (widths) in the longitudinal direction (the x direction) ofthe first conductors 121 a, 121 b, 121 c, and 121 d may be graduallyreduced from the cell region 300 side toward the end portion side of thesemiconductor device 1 while widths of the first semiconductors 121 emay be set equal to one another. Alternatively, the widths of the firstconductors may be gradually reduced in the order of the second, third,fourth, fifth, sixth seventh, eighth, and ninth conductors, and the likecounted from the cell region 300 side, for instance, and the widths ofthe first semiconductors thereafter may be set equal. Moreover, whenviewed from above (viewed in the y direction), dimensions in thelongitudinal direction of the first conductors 121 a, 121 b, 121 c, andthe like on the cell region side from a section above an end portion ofthe reduced surface layer 111 on the end portion side of thesemiconductor device 1 may be gradually reduced from the cell region 300side to the end portion side of the reduced surface layer 111, anddimensions in the longitudinal direction of the conductors in the secondconductor group 125 thereafter, or in other words, from the sectionabove the end portion side of the reduced surface layer 111 to the endportion side of the semiconductor device 1 therefrom may be set equal toone another. The dimension in the longitudinal direction (the xdirection) of the first conductor 121 a is set preferably in a rangefrom about 19 to about 35 μm, or more preferably in a range from about19 to about 30 μm, or even more preferably around 27 μm. The dimensionin the longitudinal direction (the x direction) of the first conductor121 b is set preferably in a range from about 14 to about 30 μm, or morepreferably in a range from about 14 to about 25 μm, or even morepreferably around 22 μm. The dimension in the longitudinal direction(the x direction) of the first conductor 121 c is set preferably in arange from about 4 to about 20 μm, or more preferably in a range fromabout 4 to about 18 μm, or even more preferably around 12 μm. Here, thefirst conductor group 121 may include polycrystalline silicon of thefirst conductivity type. When polycrystalline silicon of the firstconductivity type is used for the first conductor group 121, an impurityconcentration thereof may be set in a range from 1×10¹⁷ to 1×10¹⁹[/cm⁻³]. The impurity concentrations among the conductors in the firstconductor group 121 may be set either equal to one another or differentfrom one another.

Here, dimensions (widths) in the longitudinal direction (the xdirection) of the second conductors 125 a, 125 b, 125 c, and 125 d maybe gradually reduced from the cell region 300 side toward the endportion side. Alternatively, the widths in the longitudinal direction(the x direction) of the conductors in the second conductor group 125may be gradually reduced in the order of the second, third, fourth,fifth, sixth seventh, eighth, and ninth conductors, and the like countedfrom the cell region 300 side, for instance, and the widths in the xdirection of the conductors in the second conductor group 125 thereafter(in the direction away from the cell region 300) may be set equal to oneanother. Moreover, when viewed in the y direction, dimensions in thelongitudinal direction of the second conductors 125 a, 125 b, 125 c, andthe like arranged on the inside of the end portion of the reducedsurface layer 111 (the cell region 300 side) may be gradually reducedfrom the cell region 300 side to the end portion side of the reducedsurface layer 111, and dimensions in the longitudinal direction of theconductors in the second conductor group 125 thereafter, or in otherwords, from the section on the end portion side of the reduced surfacelayer 111 to the end portion side of the substrate viewed in the ydirection may be set equal to one another.

The dimension in the longitudinal direction (the x direction) of thesecond conductor 125 a is set preferably in a range from about 36 toabout 56 μm or more preferably around 46 μm. The dimension in thelongitudinal direction (the x direction) of the second conductor 125 bis set preferably in a range from about 17 to about 37 μm or morepreferably around 27 μm. The dimension in the longitudinal direction(the x direction) of the second conductor 125 c is set preferably in arange from about 7 to about 27 μm or more preferably around 17 μm. Here,the second conductor group 125 may be made of polycrystalline silicon ofthe first conductivity type.

Here, the first conductor group 121 may use one of various conductorssuch as metals. Alternatively, by forming the first conductor group 121using p-type polycrystalline silicon, it is possible to prevent externalions such as sodium ions from penetrating a portion between the firstconductor group 121 and the substrate 100. An impurity in the p-typepolycrystalline silicon may be either boron (B) or aluminum (Al), and animpurity concentration thereof is set preferably in a range from about1×10¹⁷/cm⁻³ to about 1×10¹⁹/cm⁻³ or more preferably in a range fromabout 5×10¹⁷/cm⁻³ to about 1×10¹⁸/cm⁻³. The impurity concentrationsamong the conductors in the first conductor group 121 may be set eitherequal to one another or different from one another.

In the meantime, the second conductor group 125 may use one of variousconductors such as metals. Alternatively, the second conductor group 125may include n-type polycrystalline silicon. By forming the secondconductor group 125 using the n-type polycrystalline silicon, it ispossible to prevent external ions such as sodium ions from penetratinginto the semiconductor device 1 beyond the second conductor group 125.An impurity in the n-type polycrystalline silicon may be eitherphosphorus (P) or arsenic (As), and an impurity concentration thereof isset preferably in a range from about 1×10¹⁹/cm⁻³ to about 1×10²¹ /cm⁻³or more preferably in a range from about 5×10¹⁹/cm⁻³ to about 1×10²⁰/cm⁻³. The impurity concentrations among the conductors in the secondconductor group 125 may be set either equal to one another or differentfrom one another. In the embodiment, the second conductor 125 a iselectrically connected to the emitter electrode 127. The secondconductor 125 a has a higher impurity concentration than that of thefirst conductor 121 a, and can thus improve ohmic properties of thesecond conductor 125 a and the emitter electrode 127. Moreover, bysetting the impurity concentration of the first conductor group 121approximately equal to the impurity concentration of the base region 109and setting the impurity concentration of the second conductor group 125approximately equal to the impurity concentration of the emitter regions110, it is possible to form each of the conductor units and thecorresponding region at the same time, and thus to reduce manufacturingcosts. Moreover, reliability can be easily improved by connecting theemitter electrode 127 to the second conductor 125 a located above thefirst conductor 121 a.

FIG. 3 is a diagram illustrating a cross-sectional view of an enlargedpart of FIG, 2. A thickness dl of the first insulation film 115 betweenthe first conductor group 121 and the substrate 100 is preferably largerthan a thickness d2 of the second insulation film 119 between the firstconductor group 121 and the second conductor group 125. Penetration offoreign substances from the outside into the substrate 100 can beprevented by setting a distance between the first conductor group 121and the second conductor group 125 smaller than a distance between thefirst conductor group 121 and the substrate 100. Here, the foreignsubstances from the outside include external ions such as sodium ions.For example, sodium ions contained in rainwater and the like maypenetrate into the semiconductor device 1. In this case, however, it ispossible to reduce the penetration of the sodium ions from the outsideinto a space between the substrate 100 and the first conductor group 121by reducing the distance between the first conductor group 121 and thesecond conductor group 125.

In the meantime, a width of an overlapping portion in the heightdirection (the opposite direction to the y direction in FIG. 2) of aconductor in the first conductor group 121 and a conductor in the secondconductor group 125 on the emitter electrode 127 side is preferably setlarger than a width of an overlapping portion in the height direction ofthe conductor in the first conductor group 121 and another conductor inthe second conductor group 125 on the channel stopper electrode 129side. As a specific example, the overlapping portions in the heightdirection of the conductors in the first conductor group 121 and theconductors in the second conductor group 125 are described by using FIG.3. The width of the overlapping portion in the height direction of thefirst conductor 121 a and the second conductor 125 a is indicated withw1. Meanwhile, the width of the overlapping portion in the heightdirection of the first conductor 121 a and the second conductor 125 b isindicated with w2. On the reduced surface layer 111, the width (w1) ofthe overlapping portion of the first conductor 121 a and the secondconductor 125 a on the emitter electrode 127 side is larger than thewidth (w2) of the overlapping portion of the first conductor 121 a andthe second conductor 125 b. In the meantime, the width (w2) of theoverlapping portion of the first conductor 121 a and the secondconductor 125 b is larger than a width of an overlapping portion of thefirst conductor 121 b and the second conductor 125 b. By increasing thewidth of the overlapping portion in the height direction on the emitterelectrode 127 side as described above, it is possible to reduce thepenetration of foreign substances from the outside into the substrate100. Here, the foreign substances that penetrate from the outsideinclude external ions such as sodium ions.

In this instance, dimensions in the lateral direction (the x direction)of the conductors in the first conductor group 121 and in secondconductor group 125 close to the cell region 300 may be set larger whiledimensions of the conductors in the first conductor group 121 and in thesecond conductor group 125 far from the cell region 300, namely,dimensions of the conductors in the first conductor group 121 and in thesecond conductor group 125 close to the end portion side may be setshorter. In this case, it is possible to equalize intervals between theadjacent conductors in the first conductor group 121. In addition, it ispossible to equalize intervals between the adjacent conductors in thesecond conductor group 125.

Meanwhile, in at least part of a region between the emitter electrode127 and the channel stopper electrode 129, the width of the overlappingportion in the height direction of a certain first conductor in thefirst conductor group 121 and a certain second conductor in the secondconductor group 125 may be equal to the width of the overlapping portionin the height direction of the certain first conductor in the firstconductor group 121 and another second conductor in the second conductorgroup 125 next to the certain second conductor. Alternatively, in atleast part of the region between the emitter electrode 127 and thechannel stopper electrode 129, the width of the overlapping portion inthe height direction of a certain first conductor in the first conductorgroup 121 and a certain second conductor in the second conductor group125 may be equal to the width of the overlapping portion in the heightdirection of another first conductor in the first conductor group 121next to the certain first conductor and the certain second conductor inthe second conductor group 125. In other words, there may be partially aplace where the widths of the overlapping portions remain equal from theemitter electrode 127 side to the channel stopper electrode 129 side.

For example, at the section above the reduced surface layer 111, thewidth of the overlapping portion in the height direction of theconductor in the first conductor group 121 and the conductor in thesecond conductor group 125 close to the cell region 300 may be increasedand then the widths of the overlapping portions may be gradually reducedin the direction away from the cell region 300. In addition, the widthsof the overlapping portions closer to the end portion side of thesubstrate than the section above the reduced surface layer 111 may beset equal to one another.

Here, the overlapping portion in the depth direction of the conductor inthe first conductor group 121 and the conductor in the second conductorgroup 125 close to the cell region 300 is set preferably in a range fromabout 8 to about 16 μm, more preferably in a range from 10 to 14 μm, oreven more preferably around 12 μm, for example. On the other hand, theoverlapping portion in the height direction of the conductor the firstconductor group 121 and the conductor in the second conductor group 125far from the cell region 300 is set preferably in a range from about 1to about 3 μm or more preferably around 3 μm, for example. As describedabove, it is possible to reduce the penetration of the foreignsubstances from the outside into the substrate 100 by setting theoverlapping portion in the height direction of the conductor in thefirst conductor group 121 and the conductor in the second conductorgroup 125 close to the cell region 300 larger than the overlappingportion in the height direction of the conductor in the first conductorgroup 121 and the conductor in the second conductor group 125 close tothe end portion of the substrate.

FIG. 4 is a diagram illustrating a cross-sectional view of asemiconductor device 2 according to one or more embodiments, which istaken along the II-II line in FIG. 1. This cross-sectional viewillustrates a cross-sectional portion of the termination region 400 inparticular. In comparison with FIG. 1, the embodiment of FIG. 4illustrates a structure in which an emitter electrode 227, a firstinterlayer insulation film 223, and a channel stopper electrode 229 arecovered with a protection film 251. The termination region 400 of thesemiconductor device 2 illustrated in FIG. 4 includes: a collectorelectrode 201; a collector layer 203 arranged on the collector electrode201; a field stop layer 205 arranged on the collector layer 203; a fieldstop layer 205 arranged on the collector layer 203; a drift layer 207arranged on the field stop layer 205; a base region 209 provided on thedrift layer 207 and on the cell region 300 side; a reduced surface layer211 arranged on the drift layer 207 in such a way as to come intocontact with the base region 209; and a channel stopper region 213provided on the drift layer 207 and on the end portion side. Acombination of the collector layer 203, the field stop layer 205, thedrift layer 207, the base region 209, the reduced surface layer 211, andthe channel stopper region 213 mentioned above may be simply andconceptually referred to as a substrate 200. Moreover, the semiconductordevice 2 includes: a first insulation film 215 arranged in such a way asto come into contact with the base region 209, the reduced surface layer211, the drift layer 207, and the channel stopper region 213; a firstconductor group 221 including first conductors 221 a, 221 b, 221 c, 221d, and 221 e arranged on the first insulation film 215; a secondinsulation film 219 arranged in such a way as to cover the firstconductor group 221; a second conductor group 225 including secondconductors 225 a, 225 b, 225 c, 225 d, and 225 e arranged on the secondinsulation film 219; a line 231 electrically connected to the secondconductor 225 e; a line 217 electrically connected to the line 231; thefirst interlayer insulation film 223 arranged in such a way as to coverpart of the second conductor 225 a as well as the second conductors 225b, 225 c, 225 d, and the like; a second interlayer insulation film 243arranged on the channel stopper region 213 in such as way as to comeinto contact with the line 217 and the first insulation film 215; thechannel stopper electrode 229 arranged on the channel stopper region 213in such a way as to cover the second interlayer insulation film 243 andto come into contact with the line 217; a third interlayer insulationfilm 241 arranged on the base region 209; the emitter electrode 227arranged on the base region 209 and electrically connected to the secondconductor 225 a; and the protection film 251 provided in such a way asto cover the emitter electrode 227, the first interlayer insulation film223, and the channel stopper electrode 229. The cell region 300 in FIG.4 is the same as the cell region 300 in HG. 1, and the explanationthereof is omitted herein.

Here, the semiconductor device 2 illustrated in FIG. 4 includes thesecond interlayer insulation film 243, and the channel stopper electrode229 establishes electrical connection between a junction to the channelstopper region 213 and the line 217 that is electrically connected tothe second conductor 225 e in such a way as to detour above the secondinterlayer insulation film 243. Here, the channel stopper electrode 229may establish the electrical connection in such a way as to establishphysical contact with the line 217 through another line between thefirst interlayer insulation film 223 and the second interlayerinsulation film 243, such that the line 217 and the channel stopperregion 213 are separated from each other by the second interlayerinsulation film 243 so as to avoid physical contact therebetween. In themeantime, the channel stopper electrode 229 is allowed to extend in theopposite direction (the cell side) to the x direction and iselectrically connected to the second conductor 225 e. This configurationcan inhibit sodium ions and the like from moving closer to the channelstopper region 213 and affecting an electric potential on a surface ofthe substrate 200. Here, an end in the opposite direction to the xdirection of the second conductor 225 e may extend closer to the cellregion 300 side than an end in the opposite direction to the x directionof the channel stopper electrode 229 does. When the channel stopperelectrode 229 is made of a metal, it is possible to suppress a variationin location of the semiconductor device 2 causing electric fieldconcentration. Meanwhile, the semiconductor device 2 illustrated in FIG.4 includes the third interlayer insulation film 241, and the emitterelectrode 227 is electrically connected to the second conductor 225 a insuch a way as to bypass the third interlayer insulation film 241. Here,the emitter electrode 227 may establish the electrical connection insuch a way as to establish physical contact with the second conductor225 a through another line between the first interlayer insulation film223 and the third interlayer insulation film 241. This configuration caninhibit sodium ions and the like from moving closer to a contact pointbetween the emitter electrode 227 and the third interlayer insulationfilm 241 near the base region 209 and affecting the electric potentialon the surface of the substrate 200. Here, an end in the x direction ofthe emitter electrode 227 may extend closer to the cell region 300 sidethan an end in the x direction of the second conductor 225 a does. Whenthe channel stopper electrode 229 is made of a metal, it is possible tosuppress the variation in location of the semiconductor device 2 causingthe electric field concentration.

FIG. 5 is a diagram illustrating electric potential distribution in thetermination region. Here, the horizontal axis indicates a breadth from abenchmark while the vertical axis indicates a thickness from thesubstrate surface. It is apparent that the electric potentials varygently as the dimensions of the first conductor and the second conductoron the cell side (the left side in FIG. 5) in the termination region arelonger than the dimensions of the first conductor and the secondconductor on the end portion side of the substrate. In other words, itis apparent that sodium ions are less likely to gather on the cell sidein the termination region.

FIG. 6 is a diagram illustrating the electric potential distributionrelative to the distance from the cell side to the end portion side ofthe substrate in the semiconductor device of FIG. 2. FIG. 6 is a diagramwhich particularly demonstrates a comparison between the region on thecell side where the widths of the first conductors as well as the secondconductors are large and the region on the end portion side of thesubstrate where the widths of the first conductors as well as the secondconductors are small. As plotted in FIG, 6, the electric potentialvaries gently in a region where the first conductors and the secondconductors have the large widths. On the other hand, it is apparent thatthe electric potential varies sharply in a region where the firstconductors and the second conductors have the small widths and thenvaries gently on the end portion side of the substrate, and that aninclination near the center in FIG. 6 (a part of the region of the smallwidths close to the large-width side) has a larger inclination than thaton the left side in FIG. 6 representing the cell side. In other words,it is apparent that the inclination of the electric potential on thecell side is reduced by increasing the widths of the first conductors soas to decrease the likelihood of the concentration of sodium ions andthe like on the cell side in the termination region, In the meantime,the inclination of the electric potential near the center in FIG. 6 ispreferably set about six times (three to eight times for example) aslarge as the inclination of the electric potential on the end portionside of the substrate illustrated on the right side in FIG. 6. In thisway, sodium ions and the like are even less likely to gather on the cellside in the termination region.

Other Embodiments

While the embodiments of the disclosure have been described above, it isnot to be understood that the statements and the drawings constitutingpart of this disclosure are intended to limit this disclosure. Variousalternative embodiments, examples, and operation techniques becomeobvious to those skilled in the art from this disclosure. In thiscontext, the disclosure encompasses various other embodiments notexpressly described herein. Accordingly, the technical scope of thisdisclosure is to be defined solely by the matters specifying thedisclosure concerning the appended claims that are reasonable from theabove description.

The semiconductor device disclosed in Patent Document 1 may allowpenetration of ionic substances and the like to the inside of asubstance from the outside. The penetration of the ionic substances andthe like may cause a malfunction or a failure of the semiconductordevice and occasionally reduce reliability of the semiconductor device.

According one or more embodiments described above, the semiconductoraccording to one or more embodiments described above can improvereliability.

1. A semiconductor device including a cell region and a terminationregion arranged around the cell region, comprising: a substrate; a firstsemiconductor region of a first conductivity type arranged in the cellregion on a first surface side of the substrate; a second semiconductorregion of a second conductivity type arranged in the cell region on thefirst surface side of the substrate; a channel stopper electrodearranged in the termination region on the first surface side of thesubstrate; a first electrode arranged on the first surface of thesubstrate and electrically connected to the second semiconductor region;an insulation film arranged between the channel stopper electrode andthe first electrode in the termination region of the substrate; firstconductors arranged inside the insulation film; second conductorsarranged on the insulation film; and a second electrode arranged on asecond surface side of the substrate, wherein a width of an overlappingportion in a height direction of one of the first conductors and one ofthe second conductors on the first electrode side is larger than a widthof an overlapping portion in the height direction of one of the firstconductors and one of the second conductors on the channel stopperelectrode side.
 2. The semiconductor device according to claim 1,wherein a dimension in the height direction of the insulation filmbetween the substrate and the first conductors is larger than adimension in the height direction of the insulation film between thefirst conductors and the second conductors.
 3. The semiconductor deviceaccording to claim 1, further comprising: a reduced surface layer of thesecond conductivity type arranged in the termination region on the firstsurface side of the substrate, electrically connected to the secondsemiconductor region, and having a lower impurity concentration than animpurity concentration of the first semiconductor region, whereindimensions in a longitudinal direction of the second conductors at asection above the reduced surface layer are gradually reduced from thesecond conductor electrically connected to the first electrode to thechannel stopper electrode side.
 4. The semiconductor device according toclaim 3, wherein dimensions in a longitudinal direction of the firstconductors at a section above the reduced surface layer are graduallyreduced from the first conductor arranged in the vicinity of the firstelectrode to the channel stopper electrode side.
 5. The semiconductordevice according to claim 3, wherein at least one of the secondconductors is electrically connected to the first electrode, at leastone of the second conductors is electrically connected to the channelstopper electrode, and a dimension of the second conductor electricallyconnected to the first electrode is longer than a dimension of thesecond conductor electrically connected to the channel stopperelectrode.
 6. The semiconductor device according to claim 3, wherein thewidths of the overlapping portions in the height direction of the firstconductors and the second conductors at the section above the reducedsurface layer are gradually reduced from the first conductor arrangedclose to the first electrode to an end portion of the reduced surfacelayer.
 7. The semiconductor device according to claim 6, wherein thewidths of the overlapping portions in the height direction of the firstconductors and the second conductors outside the section above thereduced surface are substantially equal to one another.
 8. Thesemiconductor device according to claim 1, wherein an end portion of thesecond conductor electrically connected to the first electrode ispositioned farther away from the cell region than an end portion of thefirst electrode is.
 9. The semiconductor device according to claim 1,wherein the first conductors comprise p-type polycrystalline silicon asa main component, and the second conductors comprise n-typepolycrystalline silicon as a main component.
 10. The semiconductordevice according to claim 9, wherein an impurity concentration of thefirst conductors is higher than an impurity concentration of the secondconductors.
 11. The semiconductor device according to claim 1, furthercomprising: a second interlayer insulation film arranged on a channelstopper region and covered with the channel stopper electrode, whereinthe channel stopper electrode and the second conductor electricallyconnected to the channel stopper electrode are in contact with eachother through a conductor between a first interlayer insulation film andthe second interlayer insulation film.
 12. The semiconductor deviceaccording to claim 1, further comprising: a third interlayer insulationfilm arranged on the second semiconductor region and covered with thefirst electrode, wherein the first electrode and the first conductorarranged close to the first electrode are in contact with each otherthrough a conductor between a first interlayer insulation film and thethird interlayer insulation film.